Pianoforte control.



M. L. SEVERY & G. B. SI NCLAIR. PIANOFORTE CONTROL. APPLICATION FILED MAR. 8, 1913.

Patented Feb. 15, 1916.

2 SHEETSSHEET I.

M. L. SEVERY & G. B. SINCLAIR.

PIANOFORTE CONTROL.

APPLICATION HLED MAR. a. 1913.

Patented Feb. 15, 1916.

2 SHEETS-SHEET 2- UNITED STATES PATENT oEEIoE.

MELVIN L. SEVERY, 0F

ARLINGTON HEIGHTS, MASSACHUSETTS, AND GEORGE B.

SINCLAIR, OF GEORGETOWN, MAINE, ASSIGNORS TO GHORALGELO COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE.

IIANOFORTE CONTROL.

Specification of Letters Patent.

Patented Feb. 15, 1916.

' Application filed March 8, 1913. Serial No. 753,013.

To all whom it may concern:

Be it known that we, MELVIN L. SEVERY, of Arlington Heights, in the county of Mid dlesex. and Commonwealth of .Massachusetts, and GEORGE B. SINCLAIR, of Georgetown, in the county of Sagadahoc and State of Maine, both citizens of the United States, haveinvented certain new and useful Improvements in Pianoforte Control, of which the following is a full, clear, and exact description.

The object of this invention is the ,construction of perfected means for varying the loudness of the vibrations of sonorous bodies in electrically actuated musical instruments.

Our invention is specifically designed for instruments of this kind wherein strings or other sonorous bodies are vibrated by electromagnets. In the course of our production of musical instruments of this character, we have discovered that, to introduce a resistance into the common circuit of all the string-actuating magnets are energized at one moment, and only one or two at another, the amount of current adapted to give a pianissimo effect to the several strings will be great enough to give a forte effect to the few. In working to overcome this defect we find that by so arranging our currentsupply that the voltage thereof can be changed at will to deliver to the stringactuating magnets a variable number of volts, the desired piano-forte effects can be produced entirely independent as to whether one or all the magnets are energized simultaneously. There are twoways in which we accomplish this. The first is by taking the current from a group of battery-cells any number of which can be cut out of or into the circuit at will. The second is by using an electric generator for feeding current to the electromagnets, the voltage of which can be similarly varied. For this we preferably employ a generator whose field is excited at will independently of the armature. The eXciter for such field may be any suitable source of electricity controlled by a variable rheostat; or it may be a plunge battery the amperage of which varies in accordance with the degree of immersion; or, it may be stop or pedal.

a multiplicity of battery cells so arranged that any desired number of cells may be cut in or cut out at will.

Our preferable exciter is a small genera-' tor the strength of whose generated current 1s varied by a rheostat controlled by a soft By moving such pedal to throw more resistance into the exciter circuit, the current'to the said field is diminished, and the voltage of the current delivered to the electromagnets correspondingly reduced.

Referring to the drawings forming part of this specification, Figure 1 is a diagram of our first mentioned method of voltage variation. Fig. 2 is a diagram of our second method of voltage variation. Fig. 3 is a diagram of a construction substantially the same as that of Fig. 2, but more complete and further improved. Fig. 4 is a view of the magnet rail and magnets carried thereby, showing the strings in cross section. Fig. 5 is a rear view of the contact blocks of our timbre controller, showing method of wiring. Fig. 6 illustrates a plurality of strings and actuating magnets, showing our method of varying the windings of the magnets for the various strings. Fig. 7 is a sectional view of a plunge battery which may be used as a variable exciter for the generator.

The numeral 1 designates a string of the usual piano type; 2 is its actuating electromagnet; 3 the key for switching current to the latter; 4 the make-and-break device for rendering the current pulsatory, and 5 the pedal controlling the voltage-varying devices. In our first-named method, said pedal acts to switch in and out the cells in accordance with the position of the brush 15 on the contacts 16. When the key 3 is depressed and the contacts 11 brought into touch, the current flows from certain of the cells through the wire 18, brush 19, make and-break disk 1, brush 21, wire 22, timbre controller 23 and wire 24 to the electromagnet 2; from here through the Wire 12, contacts 11, wire 13, pedal arm 14:, brush 15, contacts 16, and wire 17 back to the cells 6. With the pedal in the position shown, and the brush 15 in touch with the second from the bottom of the contacts 16, the current will pass through four of the cells6 in series, and so deliver current of an intensity of fss are substantially similar to those of the first form, with the exception that the battery cells and the contacts 16 are replaced by a rheostat 31, and a generator 30 having its field separately excited by a source of current 38. y

In Fig. 2, the generator is represented as driven by means of an electric motor taking its operating current from any suitable source; but such generator may be driven by any suitable prime mover, as a gasengine. The exciter 38 is also shown as driven by power taken from said motor; but, as stated above, this exciter may be a battery, or may be driven by any other-suitable means. Here, the current from the eXciter passes through the wire 40, field windings 34, wire 41, pedal arm 14, brush l5, rheostat 31 and wire 39 back to said generator or exciter 38. As represented in Fig. 2, only a limited length of resistance is in the excitercircuit, and so a strong current is delivered to said field; thereby increasing the voltage of the current delivered by the generator, 30. Depressing the pedal 5 outs in more resistance, decreases the current passing through the field windings, and so diminishes the voltage of the generated current. When the circuit is closed by the depression of a key 3, the current produced by the generator 30 flows from the armature 35 to the brush 36, wire 18, brush 19, make-and-break disk 4, brush 21, wire 22, timbre controller 23, wire 24, electromagnet 2, wire 12, contacts 11, wire 43, brush 37 and thence back to'the armature 35.

The construction shown in Fig. 3 is substantially the same as that disclosed in Fig. 2, the main difference being that here we illustrate a construction wherein several strings I and actuating magnets 2 are indicated, and an equal number of make-andbreak devices 4, 21. our timbre controller 23 somewhat more in deta il,the pedal 25 thereof being adapted for raising and lowering the frame 26 carrying the brushes 28, and thereby presenting the latter to any one of the horizontal roWs of contact blocks 27. When said brushes are in touch with the lowest roW of said contact blocks which are joined direct to the wires 22, the make-and-break devices are put into We also here show 1,171,ees

their normal relationship with their magnets 2; but when said brushes are elevated, the oblique wiring of the upper rows to the lowest row, causes make-and-break devices of different periodicities to be switched into operative connection with such magnets. This oblique wiring is also shown in Fig. 5 of the drawings hereof, and is set forth in our application Serial N 0. 273,202, filed Aug. 7, 1905, which has since the present application was originally filed, eventuated in Letters Patent N 0. 1,110,012, dated September 8, 1914.

While one marked advantage of our invention is that of enabling the number of simultaneously sounded strings to be varied to practically any extent with a substantial uniformity of loudness, as above set forth, another advantage of our invention is its production of various tone qualities. This is efiected through the timbre controller 23 .just described, and the function of which is to switch the electric periodicities normal to the magnet operating one string, to the magnet operating some other string, thereby producing new ground tones, which do not result from the length and tension of the strings, but do result from the periodicities of the impulse-producing devices which are at the same time sending pulsations into the electromagnets actuating the strings. Each of these ground tones has its own system of harmonics. In effecting this result, it is our preferred method, where the sonorous bodies are strings, to apply the frequencies or electric periodicities normal to the higher, smaller and shorter strings, larger and longer strings.

It is our discovery that the high pitched sonorous bodies produce the best results when operated by magnets of relatively low resistance, while those of lower pitch, as for example the longest strings of a piano, give the best results when operated by magnets of a resistance relatively high in proportion to the magnets of the aforesaid high strings. We have also discovered that if a periodicity normal and proper to the relatively low reslstance magnet, which we have found best suited to a high note, he switched to the relatively high resistance magnet, proper for and operating a low pitched sonorous body, the tone produced therefrom will, if current conditions remain constant, be weaker than when the body is actuated by a periodicity normally proper for it.

It s one of the objects of our invention, therefore, to increase the loudness of harmon c tones by giving to each position of the tlmbre controller an electric energy approprlateto the new conditions which the said position initiates. For example, if the position of the timbre controller brushes 28 were such that the normal periodicities will be switched down, say, an octave, the-voltage to the lower,

'of having the wire will need to be increased but a small amount in comparison with the increase needed when the controller switches the periodicities normal to the notes, down to two or three octaves below for instance. Our method of accomplishing this result, while at the same time/leaving the pedal-operated resistance 81 controlling the musical expression entirely free, is as follows: Instead 41 connected to the arm 14 as shown in the dotted line 41, and as above described, we terminate the wire 41 at the upper end of the resistance 51. The pedal 25 is provided with a brush 52 sweeping over said resistance, and this brush 52 is joined by a wire 53 to the arm 14. The normal position of the timbre controller frame 23, and hence the arm 54 of said pedal, is such as to bring the brush 52 in touch with the lowest point on the resistance 51. Consequently, when the timbre controller is not in use, the maximum resistance is in the common circuit; but as the pedal 25 is depressed to elevate the brushes 28 into contact with higher contact-blocks 27, such resistance will become less and less. This is very essential, because, as we have discovered, less power is required to vibrate a sonorous body in accordance with its fundamental, than to actuate it by pulsations corresponding to its harmonics. In other words, by using for our fundamental tones only a portion of the voltage obtainable by our apparatus, and then increasing the voltage for the new ground tones, according to the conditions obtaining in each case, we are enabled to keep the loudness'of these new ground tones equal to that of the fundamentals, or in any other relation therewith that we mav desire.

It will, of course, be obvious that whatever the loudness of thenew ground tones produced, they may be varied by the pedal 5 exactly as in the case of fundamental. tones.

The two resistances 31 and 51 are in this sense independent of each other; that put in circuit by the timbre controller merely altering the loudness of the loudest producible tone at that time, while leaving the pedal 5 free to modulate that loudness to any desirable extent. It will be seen, therefore, that our means of controlling the loudness of the new ground tones is not restricted to this particular means for controlling musical expression, although this means, on account of its convenience and simplicity, is one of our preferred forms. It being our discovery that the harmonic tones require various amounts of energy of current in the magnets actuating the sonorous bodies for a given loudness of tone, any means for varying the energy of the supplied current to produce this result or.

of varying the effectiveness of the action of the magnets upon their associated sonorous bodies comes within the scope of our distances vfrom their respective actuating invention, whether it be performed by an alteration of thevoltage or of the amperage flowing through each magnet, or by any other change of conditions.

Fig. 4 illustrates, although in an exaggerated degree, our fixed magnet rail and the string-actuating magnets 2. These magnets are shown in three groups, those in the right hand group being wound with relatively heavy wire; those in the middle group, with wire of intermediate size, and those of the low base group, with relatively fine wire. We do this because of our discovery that the higher the rapidity of magnetization and demagnetization required of the actuating electro-magnets, 2, and the resultant magnetic lag, the lesser must be the resistance given by the magnet-windings, and hence the coarser must be such wire. While theoretically such progression in coarseness of windings should extend uniformly from the lowest to the highest notes, we find that for the cheaper grade of instruments, three or four groups of different windings areordinarily sufiicient, as shown in the drawing,

than are the magnets 2 to their strings 1".

Such relative positions are obtained by simply locating between the magnets 2 and 2, and the rigid magnet rail 60, layers of suitable material, or shims 60*, until the proper distances are secured. We do this for the cheaper grades of musical instruments, wherein three or four such variations in distances serve the purpose sufliciently well. The reason for such variations is that for the fine, strongly tensioned upper treble strings, and the exceedingly rapid vibrations of them, the magnets must be close enough thereto to properly attract them, and their amplitude of vibration being small, it is possible so to locate the magnets without danger of the latter being struck. The low bass strings, on the other hand, being heavy and slow of motion, must have their actuating magnets nearer thereto than the intermediate strings which are lighter and more easily set in motion than those either above or below. Consequently, properly to equalize the loudness of the several groups of strings, they must be located at magnets such as will give the intermediate and most easily attracted strings the longest intervening space; the upper treble strings, the shortest; and the low bass an intermediate space. This is also illustrated in Fig. 6.

Although'we have shown the timbre controller 23 and the rheostats 31 and 51 as operated by means of pedals, we do not mean to restrict ourselves thereto, as hand-manipulated stops and slides can be used equallywell, as shown in our said application Serial No. 273,202; now Patent No. 1,110,012.

In our joint application Serial N 0. 380,987, filed June 26, 1907, is further disclosure and description of features more or less in common with features of this present application. To the extent that such matters are claimed in said application Serial N 0. 380,987 they are not claimed herein, but are reserved to said earlier application.

What we claim as our invention and for which we desire Letters Patent is as follows, to wit 1. A musical instrument comprising sonorous bodies actuated by electromagnets, a timbre controller for said magnets, and means whereby the strength of current delivered to said magnets is automatically varied by the operation of said timbre controller.

2. A musical instrument comprising sonorous bodies actuated by electromagnets, means for delivering electric pulsations to said magnets, a current-switching device for sending at will any selected set of pulsations into any of a plurality of magnets, and means connected and operable with said switching device for varying the voltage of the energizing current.

3. A musical instrument comprising a source of electric energy; a circuit including said source; electromagnets also included in said circuit; sonorous bodies in proximity to said electromagnets; means for producing pulsations in the electric current of the circuit; a current switching device for sending at will any selected sets of pulsations into any of a plurality of said magamass switching device for sending at will pulsations of a plurality of said magnets; means connected and operable with said switching device for varying the current strength to cor,- respond with the difl'erent adjustments of said switching device; and means independently controlling the strength of the current pulsations.

5. A musical instrument having sonorous bodies electrically actuated, means for producing a variety of tones of different timbre from any one of said bodies, and means for regulating the loudness of such tones.

6. A musical instrument having sonorous bodies electrically actuated, means for producing a variety of tones of different timbres from any one of said bodies, means for regulating the loudness of such tones, and means for controlling the loudness of such tones produced in sequence.

In testimony that we claim the foregoing invention, we have hereunto set our hands this 17th day of December, 1912.

MELVIN L. SEVERY. GEORGE B. SINCLAIR. Witnesses:

EDWARD S. CRooKET'r, ESTHER R. PRUssIAN.

any of said frequencies to any of' 

